1. Field of the Invention
The present invention relates to an image information processing apparatus for producing image information in an image file format which enables storage of image data and attribute information thereof into an arbitrary position, as well as to an image information processing apparatus for enabling entry of image information in an image file format which enables storage of image data and attribute information thereof into an arbitrary position.
2. Related Art
In association with growth of the Internet and an increase in the speed of network lines, there have recently been put into use an apparatus which distributes image data to a receiving party by way of the Internet, such as an Internet facsimile, and which exchanges information among computers through use of related-art text-dominated electronic mails or a computer program which implements equivalent functions.
Various schemes for transmitting and receiving image data by way of the Internet have already been proposed. Image data which are several pages in length, such as those pertaining to a business document, are transmitted and received while being stored in a file, such as TIFF (Tagged Image File Format) developed by Aldus Corporation in the U.S. (now a part of Adobe Systems in the U.S.). By way of an example, specifications for an image data format handled by the Internet facsimile apparatus are defined on the basis of the TIFF standards. Specifications for an image data format to be handled by an Internet facsimile are defined by a request for comments (RFC) 2301 issued by the Internet Engineering Task Force (IETF).
FIG. 9 is a view showing the configuration of a TIFF-format file (hereinafter called a “TIFF file”). The TIFF file has a tree structure beginning with a header (Header). The header consists of three information items; that is, a byte order (Byte Order), a TIFF file identifier (TIFF Identifier), and an offset (Offset of 0th IFD) of an image file directory (Image File Directory: IFD) which specifies attribution information concerning the resolution and size of a first image. The header is formed from a total of eight bytes. The first two bytes (i.e., Byte 0 and Byte 1) of a TIFF file are allocated to byte order. The byte order represents the manner in which a multi-byte value is preserved in a TIFF file. The byte order of two bytes corresponds to either “II (Little-endian Byte Order indicated by 4949.H; “.H” means a hexadecimal number)” or “MM (Big-endian Byte Order indicated by 4D4D.H).” Two bytes subsequent to the byte order (i.e., Byte 2 and Byte 3) are allocated to the TIFF file identifier. More specifically, “42 (indicated by a decimal number)” is described as the TIFF file identifier. The only requirement for determining whether or not an arbitrary data file is a TIFF file is to check the first four bytes. An offset to an image file directory is allocated to four bytes (Byte 4 to Byte 7) subsequent to the TIFF file identifier. The position of a first image file directory within a TIFF file is described as a byte offset value while the head of the TIFF file is taken as a reference. Here, an offset value A is stored in the TIFF file.
An image file directory is usually described subsequent to the header. The image file directory (IFD) is constituted of, in the order given, the number of directory entries (Number of Directory Entries), a plurality of directory entries (Directory Entries), and an offset of the next image file directory (Offset of Next IFD). The first two bytes (i.e., Byte A and Byte A+1) of the image file directory are allocated to the number of directory entries. The number of directory entries shows the number of subsequent directory entries. Here, B directory entries follow the header. Each of B directory entries (i.e., from directory entries, 0, 1, . . . B−1) is allocated 12 bytes. Various information items concerning corresponding image data (i.e., a size, a resolution, a color space, a compression encoding scheme, and a storage location) are described in the directory entries. An offset of the next image file directory is allocated four bytes subsequent to the final directory entry B−1. The position of the next image file directory is described as a byte value offset while the head of the TIFF file is taken as a reference. The present example shows that an offset value C is stored in the file. An offset of the next image file directory assuming a value of 0 means that the image file directory is the final image directory of the TIFF file.
In a TIFF file, corresponding actual image data are usually stored in succession to each of image file directories. In terms of TIFF specifications, the layout of an image file directory and image data is not defined definitely. Consequently, there is allowed a TIFF file constructed such that image data are stored in a file so as to precede a corresponding image file directory. For this reason, an information processing apparatus which decodes a TIFF file is desirably capable of processing an image file directory and image data regardless of their layouts.
For example, the Unexamined Japanese Patent Application Publication No. Hei11-127297 describes an information processing apparatus capable of processing an image file directory and image data regardless of their layouts. According to the technique described in the patent, encoded image data included in a TIFF file are stored in image memory. At a point in time when an image file directory corresponding to encoded image data stored in image memory is retrieved from a TIFF file, the encoded image data are read from the image memory and decoded. The thus-decoded image data are output. By means of storing image data into memory, print processing can be effected regardless of the layout of image data corresponding to the image file directory.
However, according to such a related-art technology, a received TIFF file is temporarily stored in memory. Hence, printing of the TIFF file cannot be effected until receipt of the TIFF file is completed. Hence, difficulty is encountered in shortening a time from initiation of receipt of a TIFF file to initiation of printing of the received TIFF file.